Mould growth on low VOC paints: Fid-Bau Portal

Mould growth on low VOC paints

Viitanen, H. / Ahola, P.

The biocides are needed to protect the paint film against microbial growth, especially bacteria, blue-stain and mould fungi. The efficiacy of different fungicides in water-borne acrylate and alkyd paints to protect pine sapwood against mould fungi was studied in a subtask of the EU project CT94-2463 in the AIR programme of DG XII. Differences in the efficiacy of the fungicides to protect the paint were found. As tested prior to weathering, the paint films with propiconazole were susceptible to mould fungi. The paint films with isothiazolon and IBPC were resistant against mould fungi but the paint films with propiconazole were susceptible to mould. The mixture of propiconazole and IPBC or propiconazole and isothiazolon performed well even at low concentration. The most effective combinations were free from mould growth after 26 weeks at RH 100 %. The natural weathering and wooden material also affected the resistance of paint films against blue-stain and mould fungi. After 6 month's natural weathering, growth of blue-stain fungi and mould fungi was found on the untreated wood and in wood without fungicides. After subsequent incubation at RH 100 %, growth of mould and blue-stain fungi was very aggresssive. Also decay was found in untreated wood and in wood without fungicides. However, the surfaces of acrylates having dipping treatment, primer and topcoat with fungicides performed relatively well after aggressive test. The surfaces from kiln dried pine and spruce sapwood were more susceptibel to fungal attack than the resawn surfaces from spruce sapwood but the application of fungicides in the different treatment layers affected the durability of outer layer against mould and blue-stain fungi.